TELE-TECH & - AmericanRadioHistory.Com

Um OALOHM... ntiltiatune gut nw.
You can depend on 4
TYPE RH
MINIATURE POWER RESISTORS
For all applications where the equipment must survive
the most severe environmental, shock, vibration, humidity
and temperature conditions.
Smallest in size; completely welded from terminal to
terminal; silicone sealed in a die -cast black anodized
aluminum housing and mounts on sub -panel for maximum
heat dissipation; impervious to moisture, salt
ions, vapor and gases.
Three wattage ranges: RH -25, 25 watts;
RH -50, 50 watts; RH -250, 250 watts.
Temperature coefficient 0.00002 /Deg. C
Ranges from 0.1 ohm to 55,000 ohms,
depending on type
Tolerances 0.05 %, 0.1 %, 0.25 %,
0.5 %, 1 %, 3 %, 5%
Conform to applicable JAN and MIL Specifications
Write for Bulletin R -21 -6
DALE PRODUCTS, INC_
Phone 2139
1304 28th Ave. Columbus, Nebraska, U.S.A.
TELEMETRY
E
At RREP, systems engineering
assumes paramount importance.
Component and assembly design
are examined critically, always
in relationship to the overall
system. And unique building
block design permits individual
components and assemblies to
be package engineered into form
iU
Export Dept t
Pan -Mar Corp.,
1270 Broadway
New York 1, N.
In Canada:
Charles W. Pointen, Ltd.
6 Alcin° Ave., Toronto
SYSTEMS
WI HETHIE G
CREATIVE
SPARK
factors to fulfill a wide variety
of applications.
It is no accident that U. S. military
agencies, foreign governments,
most aircraft companies
and many research and industrial
organizations specify RREP
telemetric data transmitting systems
for reliability under extreme
operating conditions.
CREATIVE ENGINEERING IS THE DIFFERENCE!
Technical bulletins describing RREP's complete line
of telemetering equipment available upon request.
RREP Type 1001A Crystal Controlled Transmitter.
RF power output: 3.5 to 4.5 watts into
52 -ohm load. Frequency range: 215 to 235 megacycles.
Frequency stability: ±0.005 %.
1111E15
RAYMOND ROSEN
ENGINEERING PRODUCTS, INC.
32nd & Walnut Streets, Philadelphia 4, Pennsylvania
15106 Ventura Boulevard, Sherman Oaks, California
Finned Magnetron
(Continued from page 174)
were built and tested. The dummy
magnetron used for the tests with
the various cooling fins employed
a coiled nichrome wire heater,
housed within a simulated anode
block, and a r -f output pipe connected
to the simulated anode block
(see Fig. 2). The test equipment
consisted of a positive displacement
blower supplying air, metered by a
rotameter, to a plenum chamber;
the air passed from the plenum
chamber through a transition piece
into the magnetron.
For each set of cooling fins, temperature
and pressure drop characteristics
were obtained over a
range of airflows. In all cases fin
thickness was .030 in., with .080 in.
between fins; overall fin length and
width were approximately 3 x 31/2
in. for all fins except the original
fin (Fig. 3) which was approximately
21/2 in. sq. Inlet air temperature
was 30 °C. The location of
the hot spot temperature tx,,,,px is
shown in Fig. 2.
A typical curve of (tc,n,ax tt,Inlet)
and pressure drop as a function of
airflow is given in Fig. 4 for the
set of original fins (Fig. 3). All 4
types of fin modifications, shown in
Figs. 5, 6 and 7, gave substantial
improvements over this original design.
Fig. 5 shows the first modification,
a fin with deflector vanes. The
purpose of the vanes was to force
more air to flow over the output
pipe, since the pipe temperature is
close to the anode temperature and
the pipe conducts much of the heat
away from the anode. It was
thought this would cause an increase
in local h at this region for
any given flow, and therefore demand
less air to achieve the overall
hS product required. The dummy
magnetron with a set of this type
of fins required only 29 cfm and 2.8
in. of water to have a satisfactory
hS value.
An improvement over the fin of
Fig. 5 was considered possible by
deflecting all of the air more
gradually over the outlet pipe,
thereby increasing h locally, and
reducing the loss associated with
the turning. This could be ac-
(Continued on page 178)
176 For product information, use inquiry cord on pages 209 -210 Tele -Tech & ELECTRONIC INDUSTRIES June 1956